1. Technical Field
The present invention relates to a terahertz wave detecting device, a camera, an imaging apparatus and a measuring apparatus.
2. Related Art
An optical sensor that absorbs light to convert the light into heat and converts the heat into an electric signal has been used. Further, an optical sensor in which sensitivity with respect to a specific wavelength is improved is disclosed in JP-A-2013-44703. According to this disclosure, the optical sensor includes an absorbing section that absorbs light to generate heat, and a converting section that converts the heat into an electric signal.
The absorbing section has a rectangular parallelepiped shape, in which irregularities are formed on one surface of the absorbing section in a lattice form with a predetermined interval. Light incident onto the absorbing section is diffracted or scattered, and thus, multiple absorption of light occurs. Further, light having a specific wavelength is absorbed in the absorbing section. Thus, the absorbing section can convert the light into heat in response to the light intensity of the light having the specific wavelength. One converting section is provided in one absorbing section. Further, the converting section converts a temperature change in the absorbing section into the electric signal. The specific wavelength has a wavelength of about 4 μm, and the interval of the irregularities is about 1.5 μm.
In recent years, a terahertz wave that is light having a frequency of 100 GHz to 30 THz has attracted attention. For example, the terahertz wave can be used for imaging, various measurements such as a spectral measurement, a nondestructive inspection or the like.
The terahertz wave is light having a long wavelength of 30 μm to 1 mm. When the terahertz wave is detected, according to the configuration disclosed in JP-A-2013-44703, the optical sensor increases in size. Further, since the thermal capacity of the absorbing section increases, the reaction rate is decreased, so that the detection accuracy of the optical sensor is lowered. Thus, there is a need for a terahertz wave detecting device capable of converting, even when a terahertz wave is detected, the terahertz wave into an electric signal with high accuracy.